Roles of conserved residues in the receptor binding sites of human parainfluenza virus type 3 HN protein.

Human parainfluenza virus type 3 (hPIV-3) entry and intrahost spread through membrane fusion are initiated by two envelope glycoproteins, hemagglutinin-neuraminidase (HN) and fusion (F) protein. Binding of HN protein to the cellular receptor via its receptor-binding sites triggers conformational changes in the F protein leading to virus-cell fusion. However, little is known about the roles of individual amino acids that comprise the receptor-binding sites in the fusion process. Here, residues R192, D216, E409, R424, R502, Y530 and E549 located within the receptor-binding site Ⅰ, and residues N551 and H552 at the putative site Ⅱ were replaced by alanine with site-directed mutagenesis. All mutants except N551A displayed statistically lower hemadsorption activities ranging from 16.4% to 80.2% of the wild-type (wt) level. With standardization of the number of bound erythrocytes, similarly, other than N551A, all mutants showed reduced fusogenic activity at three successive stages: lipid mixing (hemifusion), content mixing (full fusion) and syncytium development. Kinetic measurements of the hemifusion process showed that the initial hemifusion extent for R192A, D216A, E409A, R424A, R502A, Y530A, E549A and H552A was decreased to 69.9%, 80.6%, 71.3%, 67.3%, 50.6%, 87.4%, 84.9% and 25.1%, respectively, relative to the wt, while the initial rate of hemifusion for the E409A, R424A, R502A and H552A mutants was reduced to 69.0%, 35.4%, 62.3%, 37.0%, respectively. In addition, four mutants with reduced initial hemifusion rates also showed decreased percentages of F protein cleavage from 43.4% to 56.3% of the wt. Taken together, Mutants R192A, D216A, E409A, R424A, R502A, Y530A, E549A and H552A may lead to damage on the fusion activity at initial stage of hemifusion, of which decreased extent and rate may be associated with impaired receptor binding activity resulting in the increased activation barrier of F protein and the cleavage of it, respectively.

Ligand recognition and allosteric regulation of DRD1-Gs signaling complexes.

Dopamine receptors, including D1- and D2-like receptors, are important therapeutic targets in a variety of neurological syndromes, as well as cardiovascular and kidney diseases. Here, we present five cryoelectron microscopy (cryo-EM) structures of the dopamine D1 receptor (DRD1) coupled to Gs heterotrimer in complex with three catechol-based agonists, a non-catechol agonist, and a positive allosteric modulator for endogenous dopamine. These structures revealed that a polar interaction network is essential for catecholamine-like agonist recognition, whereas specific motifs in the extended binding pocket were responsible for discriminating D1- from D2-like receptors. Moreover, allosteric binding at a distinct inner surface pocket improved the activity of DRD1 by stabilizing endogenous dopamine interaction at the orthosteric site. DRD1-Gs interface revealed key features that serve as determinants for G protein coupling. Together, our study provides a structural understanding of the ligand recognition, allosteric regulation, and G protein coupling mechanisms of DRD1.

Hydrolysis of cellulose using cellulase physically immobilized on highly stable zirconium based metal-organic frameworks.

Developing a new cellulase-MOF composite system with enhanced stability and reusability for cellulose hydrolysis was aimed. Physical adsorption strategy was employed to fabricate two cellulase composites, and the activity of composite was characterized by hydrolysis of carboxymethyl cellulose. The NH2 functionalized UiO-66-NH2 MOF exhibited higher protein loading than the precursor UiO-66, due to the extra anchor sites of NH2 groups. The immobilized cellulase showed enhanced thermostability, pH tolerance and lifetime. The maximum activity attained at 55 °C could be kept 85% when used at 80 °C, and the residual activities were 72% after ten cycles and 65% after 30 days storage. The abundant NH2 and COOH groups of MOF adsorb cellulase and enhance its stability, and the resulted heterogeneity offered the opportunity of recovering composite via mild centrifuge. The findings suggest the promising future of developing cellulase-MOF composite with ultrahigh activities and stabilities for practical application.

A multifunctional Co-based metal-organic framework: heterogeneous catalysis, chemiluminescence sensing and moisture-dependent solvatochromism.

Crystalline materials with multi-catalytic applications are of great value to both fundamental research and practical applications. The platform of metal-organic frameworks (MOFs) is utilized to fabricate a microporous versatile catalyst with high stability. Self-assembly of a flexible ligand, 4-(4-carboxybenzylamino)benzoic acid (H2CBBA), with Co(ii) resulted in a 3D framework, CBBA-Co, with Co3O clusters exposed in the zigzag channels. Upon in situ activation, CBBA-Co exhibited multiple heterogeneous catalytic activities. Theoretical calculations were carried out to give insights into the catalytic process. In addition, CBBA-Co also showed promising potential in optical sensing by virtue of its catalytic activity. The luminol chemiluminescence was greatly enhanced by CBBA-Co, and linear determination of the concentration of H2O2 in the range of 0-30% was established. The successful implementation of CBBA-Co indicates the feasibility and promising future of employing MOFs as an efficient platform for the fabrication and study of multifunctional catalysts, both experimentally and theoretically.

Preparation of Paraffin@Poly(styrene-co-acrylic acid) Phase Change Nanocapsules via Combined Miniemulsion/Emulsion Polymerization.

The fast development of solid-liquid phase change materials calls for nanomaterials with large specific surface area for rapid heat transfer and encapsulation of phase change materials to prevent potential leakage. Here we report a combined miniemulsion/emulsion polymerization method to prepare poly(styrene-co-acrylic acid)-encapsulated paraffin (paraffin@P(St-co-AA)) nanocapsules. The method could suppress the shortcomings of common miniemulsion polymerization (such as evaporation of monomer and decomposition of initiator during ultrasonication). The paraffin@P(St-co-AA) nanocapsules are uniform in size and the polymer shell can be controlled by the weight ratio of St to paraffin. The phase change behavior of the nanocapsules is similar to that of pure paraffin. We believe our method can also be utilized to synthesize other core-shell phase change materials.

Novel CO2 Fluorescence Turn-On Quantification Based on a Dynamic AIE-Active Metal-Organic Framework.

Traditional CO2 sensing technologies suffer from the disadvantages of being bulky and cross-sensitive to interferences such as CO and H2O, these issues could be properly tackled by innovating a novel fluorescence-based sensing technology. Metal-organic frameworks (MOFs), which have been widely explored as versatile fluorescence sensors, are still at a standstill for aggregation-induced emission (AIE), and no example of MOFs showing a dynamic AIE activity has been reported yet. Herein, we report a novel MOF, which successfully converts the aggregation-caused quenching of the autologous ligand molecule to be AIE-active upon framework construction and exhibits bright fluorescence in a highly viscous environment, resulting in the first example of MOFs exhibiting a real dynamic AIE activity. Furthermore, a linear CO2 fluorescence quantification for mixed gases in the concentration range of 2.5-100% was thus well-established. These results herald the understanding and advent of a new generation in all solid-state fluorescence fields.

Metal-Organic Framework Photosensitized TiO2 Co-catalyst: A Facile Strategy to Achieve a High Efficiency Photocatalytic System.

A 3D metal-organic framework (ADA-Cd=[Cd2 L2 (DMF)2 ]⋅3 H2 O where H2 L is (2E,2'E)-3,3'-(anthracene-9,10-diyl)diacrylic acid) constructed from diacrylate substituted anthracene, sharing structural characteristics with some frequently employed anthraquinone-type dye sensitizers, was introduced as an effective sensitizer for anatase TiO2 to achieve enhanced visible light photocatalytic performance. A facile mechanical mixing procedure was adopted to prepare the co-catalyst denoted as ADA-Cd/TiO2 , which showed enhanced photodegradation ability, as well as sustainability, towards several dyes under visible light irradiation. Mechanistic studies revealed that ADA-Cd acted as the antenna to harvest visible light energy, generating excited electrons, which were injected to the conduction band (CB) of TiO2 , facilitating the separation efficiency of charge carriers. As suggested by the results of control experiments, combined with the corresponding redox potential of possible oxidative species, . O2- , generated from the oxygen of ambient air at the CB of TiO2 was believed to play a dominant role over . OH and h+ . UV/Vis and photoluminescence technologies were adopted to monitor the generation of . O2- and . OH, respectively. This work presents a facile strategy to achieve a visible light photocatalyst with enhanced catalytic activity and sustainability; the simplicity, efficiency, and stability of this strategy may provide a promising way to achieve environmental remediation.

Tumor vascular homing endgolin-targeted radioimmunotherapy in hepatocellular carcinoma.

Endoglin is a proliferation-associated cell membrane antigen and overexpressed in the angiogenic vasculature of solid tumors. However, the applications of endoglin (ENG)-targeted radioimmunotheray in hepatocellular carcinoma have not been reported yet. Therefore, the aim of this study was the visualization of both the development of hepatocellular carcinoma (HCC) tumor burden and therapeutic effect with ENG-targeted (131)I-anti-ENG mAb (A8), via in vivo noninvasive fluorescence imaging (NIFLI) of SMMC7721-green fluorescent protein (GFP) cells. A8 showed a dose-dependent, time-dependent suppression on the proliferation of SMMC7721-GFP cells and human umbilical vein endothelial cells (HUVECs) in vitro. Tube formation assay showed that (131)I-A8 markedly inhibits HUVECs to form extensive and enclosed tube networks. The results showed that the radiochemical purity of (131)I-A8 was 92.8 % and (131)I-A8 maintained more stable in serum than in saline and had high affinity against SMMC7721-GFP cells. The pharmacokinetics of (131)I-A8 was in accordance with the two-compartment model, with a rapid distribution phase and a slow decline phase. NIFLI exhibited a good relation between the fluorescent signal and tumor volume in vivo. Furthermore, treatment with (131)I-A8 resulted in significant tumor-growth suppression on the basis of the reducing fluorescent signal and a remarkably decreased tumor weight in treated animals. These results were further verified by RT-PCR and immunohistochemistry staining. Our findings indicate that (131)I-A8 can be used as ENG-targeted therapy for hepatocellular carcinoma, and noninvasive fluorescence imaging provides valuable information on tumor burden and effectiveness of therapy.

Evaluation of (131)I-anti-angiotensin II type 1 receptor monoclonal antibody as a reporter for hepatocellular carcinoma.

BACKGROUND: Finding a specific agent is useful for early detection of tumor. Angiotensin II type 1 receptor (AT1R) was reported to be elevated in a variety of tumors and participate in tumor progression. The aim of our study was to evaluate whether (131)I-anti-AT1R monoclonal antibody (mAb) is an efficient imaging reporter for the detection of hepatocellular carcinoma. METHODOLOGY/PRINCIPAL FINDINGS: AT1R mAb or isotype IgG was radioiodinated with (131)I and the radiochemical purity and stability of the two imaging agents and the affinity of (131)I-anti-AT1R mAb against AT1R were measured. 3.7 MBq (131)I-anti-AT1R mAb or isotype (131)I-IgG was intravenously injected to mice with hepatocellular carcinoma through tail vein, and then the whole-body autoradiography and biodistribution of the two imaging agents and the pharmacokinetics of (131)I-anti-AT1R mAb were studied. (131)I-anti-AT1R mAb and (131)I-IgG were successfully radioiodinated and both maintained more stable in serum than in saline. The (131)I-anti-AT1R mAb group showed much clearer whole-body images for observing hepatocellular carcinoma than the (131)I-IgG group. The biodistributions of the two imaging agents suggested that hepatocellular carcinoma tissue uptook more (131)I-anti-AT1R mAb than other tissues (%ID/g = 1.82±0.40 and T/NT ratio = 7.67±0.64 at 48 h), whereas hepatocellular carcinoma tissue did not selectively uptake (131)I-IgG (%ID/g = 0.42±0.06 and T/NT ratio = 1.33±0.08 at 48 h). The pharmacokinetics of (131)I-anti-AT1R mAb was in accordance with the two-compartment model, with a rapid distribution phase and a slow decline phase. These results were further verified by real-time RT-PCR, immunohistochemistry staining and Western blot. CONCLUSIONS/SIGNIFICANCE: (131)I-anti-AT1R mAb may be a potential target for early detection of tumor.

Role of N-linked glycosylation of the human parainfluenza virus type 3 hemagglutinin-neuraminidase protein.

Human parainfluenza virus type 3 (hPIV-3) is a major respiratory tract pathogen that affects infants and young children. The hPIV-3 hemagglutinin-neuraminidase (HN) protein is a multifunctional protein mediating hemadsorption (HAD), neuraminidase (NA), and fusion promotion activities, each of which affects the ability of HN to promote viral fusion and entry. The hPIV-3 HN protein contains four potential sites (N308, N351, N485 and N523) for N-linked glycosylation. Electrophoretic mobility analysis of mutated HN proteins indicated that N308, N351 and N523 sites, but not the N485 site in HN protein, were targeted for the addition of glycans in BHK-21 cells. These functional glycosylation sites were systematically eliminated in various combinations from HN to form a panel of mutants in which the roles of individual carbohydrate chains and groups of carbohydrate chains could be analyzed. Removal of individual or multiple N-glycans on the hPIV-3 HN protein had no effects on transport to the cell surface, expression and NA activity. Single glycosylation site mutants (G1, G2 and G4) not only impaired fusion promotion activity but also reduced HAD activity of HN protein, which was even more obvious for all three double mutants (G12, G14 and G24) and the triple mutant (G124). In addition, every mutant protein retained F-interactive capability that was equal to the wild-type protein capability. Interestingly, the F protein that could be co-immunoprecipitated with the G12 mutated protein or immunoprecipitated with anti-F antibody was not efficiently cleaved. For G14, G24 and G124, little cleaved F protein was detected in co-immuoprecipitation F protein assay and its total amounts where in the cell lysates. The mechanism underlying hPIV-3 HN and F protein remained associated before and after receptor engagement and the strength of the HN-receptor interaction modulated the activation of F the protein which could determine the extent of fusion. Finally, we demonstrated that single or multiple N-glycosylation site mutations inhibited fusion at the earliest stages. Taken together, these results indicated that N-glycosylation of hPIV-3 HN is critical to its receptor recognition activity, cleavage of the F protein, and fusion promotion activity, but had no influence on its interaction with the homologous F protein and NA activity.

[Study on functions of N-carbohydrate chains in human parainfluenza virus type 3 hemagglutinin-neuraminidase protein].

To determine the functions of N-carbohydrate chains in human parainfluenza virus type 3 hemagglutinin-neuraminidase(HN) protein, a PCR-based site-directed mutagenesis method was used to obtain N-glycan mutants. Protein electrophoresis rate, cell surface expression,receptor binding activity, neuraminidase activity and cell fusion promotion activity were determined. The HN proteins of single mutants (G1, G2, and G4) and multiple mutants (G12, G14, G24 and G124) migrated faster than the wild-type (wt) HN protein on polyacrylamide gels, while G3-mutated protein and wt HN protein migrated at the same position. There was no statistic difference in cell surface expression and neuraminidase activity between wt and each mutant HN protein (P>0.05), but receptor binding activity and cell fusion promotion activity of each mutant protein was reduced to significant extent (P<0.05). G1, G2 and G4 mutants exhibited re duced receptor binding activity, which was 83.94%, 76.45% and 55.32% of the wt level, respectively. G1, G2 and G4-mutated proteins also showed reductions in fusion promotion activity, which was 80.84%, 77.83% and 64.16%, respectively. Multiple mutants with G12-, G14-, G24- and G124- substitutions could further reduce receptor binding activities, 33.07%, 20.67%, 19.96% and 15.11% of the wt HN level, respectively. G12, G14, G24 and G124 mutants exhibited levels of fusion promotion activity that were only 46.360, 12.04%, 13.43% and 4.05% of the wt amount, respectively. As N-glycans of hPIV3 HN protein play an important role in receptor binding activity and cell fusion promotion activity of HN protein. We propose that the loss of N-glycans change the conformation or orientation of globular domain that is responsible for receptor binding and lower receptor binding activity and cell fusion promotion activi ty.

[Preparation and biologic activity study of (125);I-labeled anti-MIF monoclonal antibody].

AIM: Find the method to make (125);I-labeled anti-Macrophage migration inhibitory factor (MIF) mAb and investigate its in vivo biologic activity. METHODS: (1)Anti-MIF mAb was radioiodinated with Na(125);I by Iodogen method followed by purified using Sephadex G-25 gelfiltration chromatography. The labeling efficiency of (125);I-labeled anti-MIF mAb was measured. The radiochemicalpurity and the stability were assayed by paper chromatograph. (2)The immunocompetence and the in vivo biologic activity were evaluated by using ELISA and modified MMI. (3)The in vivo biodistribution of (125);I-labeled anti-MIF mAb was detected using mouse model. RESULTS: (1)The best reaction condition for labeling was: Mixed 40-100 µg Iodogen with 20-50 µg anti-MIF mAb (Iodogen(m): anti-MIF mAb(m)=2:1); added 15-30 MBq Na(125);I to Iodogen-Ab mix; kept reaction at RT for 10-15 min. The labeling efficiency of (125);I-labeled anti-MIF mAb was (90.40 ± 3.34)%. The radiochemicalpurity was (97.60 ± 1.14)%. And the specific activity was 12.2-26.0 MBq/µg. The radiochemicalpurity of (125);I-labeled anti-MIF mAb was still 90.36% after kept at 4DegreesCelsius for three days. (2)(125);I-mMIF mAb could bind to its ligand MIF in vivo with their unaffected immunocompetence and biologic activity. (3)The lungs, livers, spleens and kidneys of the experimental mice had the relative high radiocounting. CONCLUSION: These results demonstrate that the (125);I-labeled anti-mMIF mAb made by Iodogen method using the reaction condition introduced in this study had the characteristic including high labeling efficiency, high radiochemicalpurit, good in vitro stability and stable in vivo biologic activity. This study suggests that (125);I-labeled anti-mMIF mAb had the potential ability to be used in further radioimmunoimaging and targeted therapy research.

[Effect of Rapamycin and Cyclosporin A on the expression of TLR5 and Foxp3 in allorejection].

AIM: To study the effect of Rapamycin (RAPA) and Cyclosporin A (CsA) on the expression of TLR5 and Foxp3 in allotransplantation model in vivo. METHODS: The murine model of skin allotransplantation was established, and divided into three groups, injected with CsA 10 mg/(kg.d), RAPA 1.5 mg/(kg.d)) and normal saline respectively for 14 consecutive days. The grafts survival was observed daily. The expression of TLR5 and Foxp3 mRNA was detected by RT-PCR. RESULTS: The survival time was obviously longer in RAPA and CsA treated groups than control group. The expression of TLR5 mRNA in allotransplantation treated with RAPA was higher than that in control group(P<0.05) and remained at a higher level than the other two groups until day 21. TLR5 showed the highest expression on day 10 among three groups, which was the top point of allorejection. Compared with CsA group, RAPA treatment in vivo caused the higher expression of Foxp3 mRNA(P<0.05), which remained at a high level after treatment stopped. However, in CsA group, Foxp3 mRNA expression increased on day 7 and 10, and then decreased significantly on day 14. TLR5 and Foxp3 expression was positively correlated among three groups. RAPA and CsA promoted the expression of TLR5 in T cells when treated with flagellin for 6 hours in vitro and RAPA has stronger effect. CONCLUSION: RAPA and CsA can promote the expression of TLR5 and Foxp3 in allotransplantation model in vivo and flagellin enhanced this effect in vitro.

[Effect of Rapamycin on CD4(+) CD25(+) regulatory T cells in allo-transplantation tolerance model].

AIM: To study the effect of Rapamycin(Rapa) on CD4(+) CD25(+) regulatory T cells in allo-transplantation tolerance model. METHODS: The model of skin allo-transplantation was established. The recipient BALB/c mice were injected with allogeneic donor spleen cells from B6 on the day before grafting and with cyclosporine(CsA) after transplantation. T cells were purified on the day 14 from the tolerant group and cultured with Rapa and/or IL-2 in different concentrations in vitro. Mixed lymphocyte reaction (MLR) was used to analyze the specific recall reaction of T cells. Percentages of CD4(+) CD25(+) regulatory T cells were examined by flow cytometry (FCM). The expression of Foxp3 mRNA was measured by RT-PCR, and the level of IL-10 in supernatant of T cells cultured in vitro was determined by ELISA. BALB/c-SCID mice underwent allo-transplantation were given adoptive transfer of T cells treated with Rapa and/or IL-2, then the survival conditions of the grafted skin were observed daily. RESULTS: CsA plus donor splenocyte injection can prolong allograft of BALB/c significantly (P<0.05). The number of CD4(+) CD25(+) regulatory T cells and the expression of Foxp3 mRNA for T cell in the tolerant group treated with Rapa and/or IL-2 were obviously increased. Adoptive transfusion of T cells from tolerant mice treated with IL-2/Rapa obviously prolonged the allograft survival time in allografted-SCID mice. CONCLUSION: Rapa can increase the ratio of CD4(+) CD25(+) regulatory T cells in vitro and prolong the graft survival time obviously after adoptive immunity, and these effects are enhanced by low-dose of IL-2.

Radioiodine labeled anti-MIF McAb: a potential agent for inflammation imaging.

Macrophage migration inhibitory factor (MIF) is a proinflammatory cytokine that may play a role in the pathogenesis of inflammation. Radiolabeled anti-MIF McAb can be used to detect in vivo inflammatory changes. The objective of this study was to investigate in vivo biology of radioiodinated anti-MIF McAb using the inflammation model mice. Anti-MIF McAb was radioiodinated with NaI125 by Iodogen method. Animal models were induced in the mice by intramuscular injection of S. aureus, E. coli, and turpentine oil. The biodistribution studies with radioiodinated anti-MIF McAb were performed on inflammation mice. The relationship between inflammatory lesions and anti-MIF McAb binding was investigated using the percent of injected dose per gram tissue (% ID/g) of tissue samples and whole-body autoradiography. The radioactivity of I125-anti-MIF McAb in the inflammatory tissue increased gradually for three inflammation models. The highest uptake was found in S. aureus group and the lowest was in E. coli group. The uptake in turpentine oil group was average. Whole-body autoradiography showed that all inflammation foci could be visualized clearly from 24 hours after injection, but 48 hours images were much clearer in accordance with the high T/NT ratio. These results demonstrate the ability of radioiodinated anti-MIF McAb to measure in vivo inflammatory events represented by high expression of MIF and suggests that radiolabeled anti-MIF McAb warrants further investigation as a potential inflammation-seeking agent for imaging to detect inflammatory disorders.

[Effects of long-term installation of intrauterine devices on intrauterine microenvironment].

OBJECTIVES: To study the effect of long-term installation of intrauterine devices (IUD) on the intrauterine microenvironment. METHODS: Eighty-nine healthy 26 - 50-year-old women undergoing physical examination or having their IUD removed were recruited. Among them 62 had used IUDs, including 32 inert IUD (I-IUD) and 30 copper releasing IUD (T-IUD), for 5 - 20 years, and 27 women without installation of IUD were used as controls. In the 3rd to 13th day of menstrual cycle, 3 ml of irrigation of intrauterine cavity were collected to examine the concentrations of tumor necrosis factor-alpha (TNF-alpha), interleukin 2 (IL-2) and secretary IgA (SIgA) by radioimmunoassay (RIA). Hysteroscopy was used to obtain 3 pieces of endometrium at the place where the IUD was attached for each subject. Three pieces of endometrium were curretted from each control during the proliferative stage. Thirty specimens of endometrium, including 10 cases with I-IUD, 10 cases with T-IUD, and 10 control cases were used to examine the distribution of T cell subset by immunohistochemistry. Fifteen specimens of endometrium, including 6 cases with I-IUD, 6 cases with T-IUD, and 3 control cases, were used to examine the endometrial ultrastructure by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Twenty-five specimens of endometrium, including 10 cases with I-IUD, 10 cases with T-IUD, and 5 control cases, were used to detect the expression and mutation of P16, P53 and K-ras by PCR-SSCP technique. RESULTS: There was no significant difference in TNF-alpha level in the irrigation among the three groups (P > 0.05). IL-2 and SIgA levels (0.39 +/- 0.18) microg/L and (2000 +/- 1224) microg/L respectively) in the T-IUD group were significantly lower than those in the control group (0.96 +/- 0.15) microg/L and (3377 +/- 1906) microg/L respectively, both (P < 0.05). There was a significant difference in the population of T lymphocytes (CD(8)(+) and CD(4)(+) lymphocytes) between the T-IUD group and control group (P < 0.05). SEM and TEM showed no necrosis and atypia in the endometrial cells of I-IUD group and T-IUD group. There was no positive expression of gene p16, p53 and K-ras in the endometrium of the three groups. CONCLUSION: It is safe and effective using I-IUD or T-IUD for a long time, however, T-IUD has some effects on intrauterine local immune function.